Generating High Dynamic Voltage Boost

ABSTRACT

Devices, systems, and methods are provided for generating a high, dynamic voltage boost. An integrated circuit (IC) includes a driving circuit having a first stage and a second stage. The driving circuit is configured to provide an overdrive voltage. The IC also includes a charge pump circuit coupled between the first stage and the second stage. The charge pump circuit is configured generate a dynamic voltage greater than the overdrive voltage. The IC also includes a bootstrap circuit coupled to the charge pump circuit, configured to further dynamically boost the overdrive voltage of the driving circuit.

PRIORITY CLAIM

The present application is a continuation to U.S. application Ser. No.16/165,047, filed Oct. 19, 2018, which claims priority U.S. ApplicationNo. 62/575,565, filed Oct. 23, 2017, the contents of which areincorporated by reference herein in their entirety.

FIELD

The technology described in this disclosure relates generally toelectronic devices and more particularly to high-side integrated drivercircuits.

BACKGROUND

High-side integrated driver circuits implemented by Gallium Nitride(GaN) High Electron Mobility Transistors (HEMT) enable high-powerthroughput of various circuitry. HEMTs have a variety of applicationsincluding drive operations of discrete power transistors.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a schematic diagram of a first exemplary semiconductor devicein accordance with various embodiments of the present disclosure.

FIG. 2 is a schematic diagram of a second exemplary semiconductor devicein accordance with various embodiments of the present disclosure.

FIG. 3 is another schematic diagram of a third exemplary semiconductordevice in accordance with various embodiments of the present disclosure.

FIG. 4 is a schematic diagram of the charge pump circuit in accordancewith various embodiments of the present disclosure.

FIG. 5 is a schematic diagram of the voltage multiplier of FIG. 4 inaccordance with various embodiments of the present disclosure.

FIG. 6 is a schematic circuit diagram illustrating the clock generatorat the output of the ring oscillator of FIG. 4 in accordance withvarious embodiments of the present disclosure.

FIG. 7 is a schematic circuit diagram illustrating the ring oscillatorof FIG. 4 in accordance with various embodiments of the presentdisclosure.

FIG. 8 is another schematic diagram of a fourth exemplary semiconductordevice in accordance with various embodiments of the present disclosure.

FIG. 9 is another schematic diagram of a fifth exemplary semiconductordevice in accordance with various embodiments of the present disclosure.

FIG. 10 is another schematic diagram of a sixth exemplary semiconductordevice in accordance with various embodiments of the present disclosure.

FIG. 11 is a flow chart of a first exemplary method of driving a powertransistor in accordance with various embodiments of the presentdisclosure.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Field-effect transistors (FETs) are transistors that operate anelectrical device using an electric field. HEMTs, such as GaN HEMTs area type of FET. Due to high current density, high breakdown voltage, andlow operational resistance, HEMTs are suitable for use in high-powerapplications. A HEMT device includes a channel layer and an activelayer. A two-dimensional electron gas (2DEG) is generated in the channellayer, adjacent an interface with the active layer. The 2DEG is used inthe HEMT structure as charge carriers, which enables current flow withinthe device. A consideration in designing HEMT structures involvesbreakdown voltage improvements. A breakdown voltage of an HEMT structureis a drain-to-gate voltage at which the drain-to-gate current sharplyincreases. A high breakdown voltage indicates the ability of the HEMTstructure to withstand a high drain-to-gate voltage without beingdamaged and/or exhibiting irregular current behaviors.

HEMTs, such as GaN HEMTs, have a variety of useful applications. GaNHEMTs is capable of delivering large amounts of power because of theirunique combination of material characteristics including high breakdownfields, wide bandgaps (e.g., 3.36 eV for GaN at room temperature), highcurrent density, large conduction band offset, and high saturatedelectron drift velocity. Specifically, in one example, GaN HEMTs can beused in power conversion and radio frequency (RF) power amplifier(PA)/switch applications, where GaN HEMTs typically have smaller formfactors compared to Silicon (Si) based transistors. Due in part to lowhole mobility within p-type components along with a two-dimension holegas (2DHG) band structure, p-type HEMTs are less favorable for use thanan n-type GaN HEMT for the embodiments described herein. Because ofthis, n-type GaN HEMTs are sometimes integrated within variousintegrated circuits instead of p-type HEMTs.

Enhancement mode HEMT (E-HEMT) and depletion mode HEMT (D-HEMT) areexample n-type HEMTs. An E-HEMT requires a positive gate voltage toattract electrons towards the gate or an appropriate doping level in aneighboring barrier to attract electrons toward the gate. Electronsattracted toward the gate form a 2DEG and enable current flow within theE-HEMT. In other words, an E-HEMT is turned on/activated by pulling thegate terminal thereof to a voltage level higher than a level of athreshold voltage, V_(th).

Conversely, a D-HEMT is in an on state at a zero gate-source voltage asformation of a 2DEG occurs even without positive gate-source voltage. Inother words, a D-HEMT is in an on state at the zero gate-source voltageand turns off when a negative gate voltage is applied. As such, it has anegative threshold voltage (e.g., −1.0V).

Static current within an integrated circuit can cause damage to itselectrical components in addition to increase overall power consumption.In order to minimize static current of integrated circuits, it may benecessary to limit the usage of D-HEMTs as pull-up devices and primarilyutilize E-HEMT devices instead. This is because D-HEMTs are operating instatic conditions with a zero gate voltage. Having a multistage E-HEMTdevice can help to minimize static current within the integratedcircuit. Each stage of an E-HEMT device, however, can consume at leastone threshold voltage, V_(t) (e.g., ˜2V when Vt is ˜1.5V having a 3-σvariation of approximately 0.5V), to turn on, which ultimately decreasesthe initial input voltage level such that an output voltage is lowerthan the input voltage to remainder of the integrated circuit. In orderto provide a voltage (e.g., overdrive voltage) sufficient for theremainder of the integrated circuit, ample gate voltage, V_(gs), isprovided to the first stage of the multi-stage E-HEMT device. Theoverdrive voltage, in accordance with some embodiments, can be providedusing a combination of internal bootstrap circuits and a charge pumpcircuit. This combination can also minimize the number of D-HEMT devicesin a multistage driving circuit and reduce the static current of adriving circuit (or high-side driver).

FIG. 1 is a schematic diagram of a first exemplary semiconductor device100 in accordance with various embodiments of the present disclosure.Semiconductor device 100 is an integrated circuit device having aplurality of stages for driving power transistor 195 and any otherelectronic components coupled thereto. The use of bootstrap circuits150, 160 and charge pump circuit 180 enable an overdrive voltage to passthrough the semiconductor device 100. The overdrive voltage drives powertransistor 195 and any additional components coupled thereto. With theoverdrive voltage, the power transistor 195 and any additionalcomponents can operate at rated electrical levels. The variousembodiments described herein can also minimize static current or othercurrent losses to enable more efficient power delivery.

In accordance with some embodiments, the semiconductor device 100 (e.g.,an integrated circuit (IC)), includes source voltage pin 110, high-sidereference voltage pins 120 a, 120 b, an input voltage pin 130, anhigh-voltage power supply pin 140, a bootstrap voltage pin 150 a,bootstrap circuits 150, 160, a driving circuit 170, a charge pumpcircuit 180, a charge pump voltage pin 180 a, a bootstrap capacitor 190,and a power transistor 195. In this embodiment, the semiconductor device100 is implemented using HEMTs, each of which includes first and secondsource/drain terminals and a gate terminal. In an alternativeembodiment, the semiconductor device 100 is implemented using acombination of HEMTs and metal-oxide-semiconductor field-effecttransistors (MOSFETs).

In this embodiment, the semiconductor device 100 further includes apackage, which encapsulates the power transistor 195, the drivingcircuit 170, bootstrap circuits 150, 160, and the charge pump circuit180 therein, and into which the voltages pins 110, 120 a, 120 b, 130,and 140 extend.

The source voltage pin 110 is configured to be connected to an externalpower source, whereby the source voltage, V_(DD), e.g., 6.0V, is appliedthereto. The source voltage is provided to bootstrap circuit 150 andcharge pump circuit 180. The high-side reference voltage pins 120 a, 120b are configured to be connected to a switching node of a half- orfull-bridge power converter, whereby a load (e.g., an inductive load, acapacitive load, or a combination thereof) is connected thereto. Theinput pin 130 is configured to be coupled to an external signal source,e.g., a pulse-width modulation (PWM) circuit, whereby an input signalthat transitions between a low voltage level (e.g., a level of thereference voltage, V_(SS), ˜0V), and a high voltage level (e.g.,6˜650V), is applied thereto. The high-voltage power supply pin 140 isconfigured to be connected to high-voltage power supply (e.g. 650V).Power transistor 195 coupled to output pin (or switching node) 120 a/120b provides the driving voltage for a load coupled thereto. Powertransistor 195 in accordance with some embodiments requires a minimumgate voltage for operation (e.g., 652V). Bootstrap voltage pin 150 a andcharge pump voltage pin 180 a are electrical points which provideadditional voltage to enable operation of power transistor 195.Operation of power transistor 195 enables operation of additionalcomponents coupled to output pin 120 b.

A supply voltage, V_(DD), is provided to a charge pump circuit 180. Thecharge pump circuit 180 is coupled to bootstrap circuit 160. The chargepump circuit 180 provides a dynamic charge pump voltage boostingvoltages of driving circuit 170, as described in more detail in FIG. 2.Due the voltage losses associated with electrical components of drivingcircuit 170 as described in more detail in FIG. 2, significantly largedynamic charge pump voltage is needed to provide substantial overdrivevoltage at the first voltage stage in order to provide sufficientvoltage to the remaining components of the integrated circuit, inparticular to the output pin 120 b. In order to achieve a near full-railpull-up voltage and fast slew rate of the semiconductor device 100, alarge overdrive voltage may be necessary for power transistor 195 (e.g.,V_(gs)−V_(t)>>0).

FIG. 2 is a schematic diagram of a second exemplary semiconductor device200 in accordance with various embodiments of the present disclosure. Inthis embodiment, the power transistor 195 is a III-V compoundsemiconductor-based, e.g., GaN-based, E-HEMT and has a high voltagerating, e.g., above 100V or 650V, depending on applications. In analternative embodiment, the power transistor 195 is a depletion-modeHEMT. In some embodiments, the power transistor 195 may be any compoundsemiconductor-based, e.g., II-VI or IV-IV compound semiconductor-based,HEMT. As illustrated in FIG. 2, the second source/drain terminal of thepower transistor 195 is coupled to the output pins 120 a/120 b and thefirst source/drain terminal is coupled to a high-voltage power supplypin 140.

The driving circuit 170 is configured to provide sufficient voltage todrive the power transistor 195. Driving circuit 170 includes a pluralityof stages 170 a, 170 b, 170 c, 170 d that each operate as an inverter.In accordance with some embodiments, each of the stages 170 b and 170 dincludes a pair of E-HEMTs E1, E2, E3, E4. Stage 170 c includes threeE-HEMTs E5, E6, E7. Due to electrical configuration of the E-HEMTs E3,E6, E1 as source followers, each stage 170 b, 170 c, 170 d can consumeat least one threshold voltage, V_(t), drop across each transistor(e.g., approximately 2V for V_(t) of approximately 1.5V with 3-σvariation of approximately 0.5V).

The first source/drain terminal of the E-HEMT E1 of stage 170 d iscoupled to the second source/drain terminal of E-HEMT E2 and to the gateterminal of the power transistor 195. The second source/drain terminalof the E-HEMT E1 of stage 170 d is coupled to bootstrap voltage pin 150a.

The first source/drain terminal of the E-HEMT E6 of stage 170 c iscoupled to the second source/drain terminal of E-HEMT E7 and to the gateterminal of the E-HEMT E1 of stage 170 d. The second source/drainterminal of E-HEMT E6 is coupled to a first terminal of bootstrapcapacitor 190. The second terminal of bootstrap capacitor 190 is coupledto the gate of power transistor 195, the first source/drain terminal ofE-HEMT E2 of stage 170 d, and the second source/drain terminal of E-HEMTE1 of stage 170 d. The gate of E-HEMT E5 is coupled to the secondsource/drain terminal of E-HEMT E5, the bootstrap voltage pin 150 a, andthe second source/drain terminal of E-HEMT E1 of stage 170 d.

The first source/drain terminal of E-HEMT E3 of stage 170 b and thesecond source/drain terminal of E-HEMT E4 are coupled to each other andto the gate terminal of E-HEMT E6 of stage 170 c. The secondsource/drain terminal of E-HEMT E3 is coupled to charge pump pin 180 a.

The stage 170 a includes a D-HEMT D and an E-HEMT E8. The firstsource/drain terminal and the gate terminal of the D-HEMT D and thefirst source/drain terminal of the E-HEMT E8 of stage 170 a are coupledto each other and to the gate terminal of the E-HEMT E3 of stage 170 b.

The second source/drain terminals of the E-HEMTs E2, E4, E7, E8 of thestages 170 a, 170 b, 170 c, 170 d are coupled to each other and to thehigh-side reference voltage pins (or switching node) 120 a, 120 b. Thegate terminals of the E-HEMTs E2, E4, E7, E8 of the stages 170 a, 170 b,170 c, 170 d are coupled to each other and to the input pin 130.

Bootstrap circuit 160 is configured to generate a bootstrap voltage,V_(BS), greater than the source voltage, V_(DD) by a charge pumpvoltage, and includes a diode D1 and a capacitor C1. In this embodiment,the diode D1 is a two-terminal diode, i.e., has anode and cathodeterminals. The anode terminal is coupled to charge pump circuit 180 andthe cathode terminal is coupled to the second source/drain terminal ofD-HEMT D of stage 170 a, the second source/drain terminal of E-HEMT E3of stage 170 b, and capacitor C1 (via charge pump voltage pin 180 a). Inother words, the capacitor C1 is coupled between charge pump voltage pin180 a and the high-side reference voltage pins (or switching nodes) 120a, 120 b. It will be appreciated that, after reading this disclosure,the bootstrap circuit 160 and charge pump circuit 180 may be of anysuitable construction so long as it achieves the intended purposedescribed herein. In accordance with some embodiments, an examplesuitable charge pump circuit 180 is described in FIG. 4.

Bootstrap circuit 150 is also configured to generate a bootstrapvoltage, V_(BS), greater than the source voltage, V_(DD), and includes adiode D2 and a capacitor C2. In this embodiment, the diode D2 is atwo-terminal diode, i.e., has anode and cathode terminals. The anodeterminal of diode D2 is coupled to source voltage, V_(DD), and chargepump circuit 180. The cathode terminal of diode D2 is coupled to a firstterminal of capacitor C2, the gate terminal and second source/drainterminal of E-HEMT E5 of stage 170 c, and the second source/drainterminal of E-HEMT E1 of stage 170 d (via external bootstrap voltage pin150 a). A second terminal of capacitor C2 is coupled to the high-sidereference voltage pins (or switching node) 120 a, 120 b.

The charge pump circuit 180 includes an input terminal connected to thesource voltage pin 110 and an output terminal. The charge pump circuit180 is configured to generate a charge pump voltage, V_(CP), at theoutput terminal thereof greater than the source voltage, V_(DD), at theinput terminal thereof. The output terminal of the charge pump circuit180 is coupled to the anode of diode D1 of internal bootstrap circuit160.

It should be understood, as illustrated in FIG. 2, that each of theE-HEMTs E1, E2, E3, E4, E5, E6, E7, E8 and D-HEMT D, aside from thefirst and second source/drain terminals and the gate terminals, furtherincludes a bulk. In an embodiment, the bulks of the E-HEMTs E1, E2, E3,E4, E5, E6, E7, E8 and D-HEMT D are coupled to each other and to thehigh-side reference voltage pins 120 a, 120 b. In another embodiment,the bulks of the E-HEMTs E1, E2, E3, E4, E5, E6, E7, E8 and D-HEMT D arecoupled to each other and to the source voltage pin 110. Powertransistor 195 also can include a bulk coupled to either the high-sidereference voltage pins 120 a, 120 b or source voltage pin 110.

In operation, when the input signal at the input pin 130 transitionsfrom the low voltage level, e.g., 0V, to the high voltage level, e.g.,6.0V with respect to the voltage at the high-side reference node (120a/120 b), the E-HEMTs E2, E4, E7, E8 of the stages 170 a, 170 b, 170 c,170 d are turned on/activated. As a result, a deactivating voltage,which corresponds to the reference voltage, V_(SS), appears at the gateterminals of the E-HEMTs E1, E3, E6 of the stages 170 b, 170 c, 170 d.This turns off/deactivates the E-HEMTs E1, E3, E6 of the stages 170 b,170 c, 170 d. This, in turn, charges the bootstrap capacitor 190. Atthis time, the D-HEMT D of the stage 170 a is activated and operates asa resistor, the charge pump circuit 180 generates the charge pumpvoltage, V_(CP), at the output terminal thereof, and thus a staticcurrent flows through diode D to the high-side reference node 120 a. Atthe same time the bootstrap capacitor C1 is charged. It is noted that,by virtue of the stages 170 b, 170 c, 170 d between the stage 170 a andthe power transistor 150, the driving circuit 170 of the presentdisclosure has a minimal static current.

In a subsequent operation, when the input signal at the input pin 130transitions from the high voltage level back to the low voltage level,the E-HEMTs E2, E4, E7, E8 of the stages 170 a, 170 b, 170 c, 170 d aredeactivated. At this time, the D-HEMT D of the stage 170 a is activatedand operates as a resistor, the charge pump circuit 180 generates thecharge pump voltage, V_(CP), e.g., 16.0V, at the output terminalthereof, and an activating voltage that corresponds to the charge pumpvoltage, V_(CP), appears the cathode terminal of diode D1 and the gateterminal of E-HEMT E3 of the stage 170 b. By virtue of the charge pumpcircuit 180, an activating voltage, a level of which is high enough toactivate the E-HEMT E6 of the stage 170 c, e.g., 14V after one Vt dropof 2V at E-HEMT E3 of the stage 170 b, appears at the gate terminal ofthe E-HEMT E6 of the stage 170 c. By virtue of the external bootstrapcircuit 150, a supply voltage of 656V appears at the drain of E-HEMT E1of the stage 170 d. After one more threshold voltage Vt drop of 2V atE-HEMT E6 of the stage 170 c, a high enough voltage, e.g., 12V+650Vappears at the gate terminal of the E-HEMT E1 of the stage 170 d. As aresult, a driving voltage, V_(drive), substantially equal to the sourcevoltage, V_(DD) plus high supply voltage (e.g. 6V+650V=656V), appears atthe gate terminal of the power transistor 195.

In an alternative embodiment, the semiconductor device 100 is dispensedwith the power transistor 195, the high-side reference voltage pins 120a, 120 b, and the high voltage power supply pin 140. In such analternative embodiment, the semiconductor device 100 further includes apower transistor pin (not shown) that extends into the package and thatis connected to the first source/drain terminals of the E-HEMTs E1, E2of the stage 170 d.

FIG. 3 is a schematic diagram of a third exemplary semiconductor device300 in accordance with various embodiments of the present disclosure.This embodiment differs from the semiconductor device 200 in that thedriving circuit 170 of semiconductor device 300 further includes one ormore stages 310 between stages 170 b, 170 c. The construction as suchfurther lowers the static current of the driving circuit 170 ofsemiconductor device 300.

FIG. 4 is a schematic diagram of the charge pump circuit 180 inaccordance with various embodiments of the present disclosure. Thecharge pump circuit 180 includes a ring oscillator 410, a clockgenerator 420, and a voltage multiplier 430. The ring oscillator 410provides an output voltage to the clock generator 420. The clockgenerator 420 provides a complement pair of clock voltages (e.g.,V_(clock), V_(clockbar)) to voltage multiplier 430. FIG. 5 is aschematic diagram of the voltage multiplier 430 in accordance withvarious embodiments of the present disclosure. As illustrated in FIG. 5,the voltage multiplier 430 is between the input and output terminals ofthe charge pump circuit 180. In accordance with some embodiments, thevoltage multiplier 430 is a Dickson voltage multiplier/charge pump andincludes stages 510, 520, 530, 540, 550, each of which includes adiode-connected E-HEMT and a capacitor (C₁, C₂, C₃, C₄, C₅).

FIG. 6 is a schematic diagram of the clock generator 420 in accordancewith various embodiments of the present disclosure. As illustrated inFIG. 6, the clock generator 420 includes a true module 610 and acomplement module 620. The true module 610 has input and outputterminals, is configured to generate a true clock signal, V_(clock), atthe output terminal thereof, and includes stages 610 a, 610 b, 610 cbetween the input and output terminals thereof. The complement module620 has input and output terminals, is configured to generate at theoutput terminal thereof a complement clock signal, V_(clockbar), that isa complement of the true clock signal, V_(clock), and includes stages620 a, 620 b, 620 c between the input and output terminals thereof. Eachof the stages 610 a, 610 b, 610 c of the true module 610 and the stages620 a, 620 b, 620 c of the complement module 620 includes a pair ofHEMTs, one of which is a D-HEMT and the other of which is an E-HEMT. Thestage 610 b of the true module 610 includes a pair of E-HEMTs.

It is noted that, since the true and complement modules 610, 620 havethe same number of stages, i.e., three in this embodiment, the trueclock signal, V_(clock),/complement clock signal, V_(clockbar), does notlead/lag the complement clock signal, V_(clockbar),/true clock signal,V_(clock). As such, the true clock signal, V_(clock), and the complementclock signal, V_(clockbar), are substantially 180° out-of-phase witheach other.

Although the clock generator 420 is exemplified such that the true andcomplement modules 610, 620 thereof includes three stages, it will beappreciated that, the true and complement modules 610, 620 may includeany number of stages.

With further reference to FIG. 5, the capacitors C of the stages 510 and530 are connected to each other and to the output terminal of the truemodule 610, whereas the capacitors C of the stages 520 and 540 areconnected to each other and to the output terminal of the complementmodule 620.

FIG. 7 is a schematic circuit diagram illustrating the ring oscillator410 in accordance with various embodiments of the present disclosure. Asillustrated in FIG. 7, the ring oscillator 410 includes a feedforwardoscillating module 710, a feedback oscillating module 720, and anenabling module 730. The feedforward oscillating module 710 has inputand output terminals, is configured/operable to generate an oscillationsignal (OSC) at the output terminal thereof, and includes stages (forsimplicity purpose, only one of the stages of the feedforwardoscillating module 710 is labeled as 640) between the input and outputterminals thereof. The feedback oscillating module 720 has input andoutput terminals connected to the output and input terminals of thefeedforward oscillating module 710, respectively, is configured toroute/feed the oscillation signal (OSC) at the output terminal of thefeedforward oscillating module 710 back to the input terminal of thefeedforward oscillation module 710, and includes stages (for simplicitypurpose, only one of the stages of the feedback oscillating module 720is labeled as 750). Each of the stages of the modules 710, 720 includesa pair of HEMTs, one of which is a D-HEMT and the other of which is anE-HEMT.

With further reference to FIG. 6, the input terminals of the true andcomplement modules 610, 620 are connected to each other and to theoutput terminal of the feedforward oscillating module 710.

In operation, when a voltage at the gate terminal of the HEMT of theenabling module 730 transitions from the low voltage level to the highvoltage level, the feedforward oscillating module 710 generates theoscillation signal (OSC) at the output terminal thereof. As a result,the true and complement modules 610, 620 generate the true andcomplement clock signals, V_(clock) and V_(clockbar), at the outputterminals thereof, respectively, whereby the voltage multiplier 430generates the charge pump voltage, V_(CP), at the output terminal of thecharge pump circuit 180.

It will be appreciated that, after reading this disclosure, the chargepump circuit 180 may be of any suitable construction so long as itachieves the intended purpose described herein.

FIG. 8 is another schematic diagram of a fourth exemplary semiconductordevice 800 in accordance with various embodiments of the presentdisclosure. The fourth exemplary semiconductor device 800 includes aboot-strapped inverting buffer circuit 810. Boot-strapped invertingbuffer circuit 810 includes one or more stages 870 a, 870 b, 870 c,which each operate as an inverter. Stage 870 a includes two E-HEMTs E81,E82 and a D-HEMT D80. Stage 870 b includes two E-HEMTs E83, E84. Stage870 c include two E-HEMTs E85, E86. Each stage 870 a, 870 b, 870 c canconsume at least one threshold voltage, V_(t), drop across eachtransistor (e.g., approximately 2V for V_(t) of approximately 1.5V with3-σ variation of approximately 0.5V).

An input voltage is provided to stage 870 a via a gate terminal ofE-HEMT E82, E84, and E86. A first source/drain terminal of E-HEMT E82 iscoupled to a second source/drain terminal of D-HEMT D80 and a gateterminal of E-HEMT E85. The gate terminal of D-HEMT D80 is coupled tothe second source/drain terminal of D-HEMT D80 and second source/drainterminal of E-HEMT E82. The second source/drain terminal of D-HEMT D80is coupled to a first source/drain terminal of E-HEMT 81. The gateterminal of E-HEMT E81 is coupled to the second source/drain terminal ofE-HEMT E81, the second source/drain terminal of E-HEMT E83 of stage 870b, the second source/drain terminal of E-HEMT E85 of stage 870 c, andexternal bootstrap voltage pin 150 a. The second source/drain terminalof D-HEMT D80 and the first source/drain terminal of E-HEMT E81 iscoupled to a first terminal of capacitor 890. A second terminal ofcapacitor 890 is coupled to the first source/drain terminal of E-HEMTE83 and the second source/drain terminal of E-HEMT E84. The firstsource/drain terminal of E-HEMT E85 is coupled to the secondsource/drain terminal of E-HEMT E86 and the gate terminal of E-HEMT E8.

External bootstrap circuit 150 is coupled to boot-strapped invertingbuffer circuit 810 via a first source/drain terminal of E-HEMT E83.Boot-strapped inverting buffer circuit 810 is configured to reduce theinput loading at the gate terminal of E8 of stage 170 a. The gateterminal of E8 is subject to large load values resulting from theoperation of E-HEMT E82, E84, E7, and E2 as those E-HEMTS are requiredto be significantly large in order to pull low at the gate terminal ofpower transistor 195. Input loading at the gate terminal E-HEMT E82 ismuch less as it sees smaller loads from E-HEMT E82, E84, and E86.

FIG. 9 is another schematic diagram of a fifth exemplary semiconductordevice 900 in accordance with various embodiments of the presentdisclosure. Semiconductor device 900 includes a minimal stagedboot-strapped driver (e.g., stage 170 a and 170 d). In this embodiment,semiconductor device 900 is able to provide a gate voltage ofapproximately 662V (vs a maximum of 654V for a multiple-bootstrappeddriver such as the embodiment of FIG. 2). In accordance with thisembodiment charge pump circuit 180 can provide a voltage output to diodeD1 of approximately 14V.

FIG. 10 is another schematic diagram of a sixth exemplary semiconductordevice 1000 in accordance with various embodiments of the presentdisclosure. In accordance with this embodiment charge pump circuit 1080can provide a voltage output to diode D1 of approximately 10V. Anoverdrive voltage (e.g., V_(ovd)˜V_(gs)−V_(t)) of approximately 0.5V isprovided to the gate terminal of E-HEMT E1. This overdrive voltage inturn provides a sufficient voltage to the gate terminal of powertransistor 195.

FIG. 11 is a flow chart 1100 of a first exemplary method of driving apower transistor in accordance with various embodiments of the presentdisclosure. The method is applicable to a wide variety of underlyingstructures. But for ease of understanding, the steps of FIG. 11 aredescribed with reference to structures depicted in FIGS. 1-4 and 8-10.An input voltage is received, at 1110, by a charge pump circuit of anintegrated circuit. The charge pump circuit generates, at 1120, adynamic charge pump voltage configured to drive a first voltage stageand a second voltage stage of the integrated circuit. The charge pumpcircuit provides, at 1130, a dynamic charge pump voltage to a bootstrapcircuit of the integrated circuit. The bootstrap circuit generates, at1140, a boosted voltage based on the dynamic charge pump voltage to thefirst stage. The second stage generates, at 1150, an overdrive voltagebased on the voltage to drive a power transistor of the integratedcircuit.

Use of the various circuits and configurations as described herein canenable the generations of high dynamic boost voltages to driveelectronic components coupled thereto. Utilizing the combination ofE-HEMT and D-HEMT devices as described herein can minimize the levels ofstatic current within an integrated circuit. The less static currentwithin the integrated circuit, the less power the integrated circuitconsumes and the less potential damage the circuit can experience. Thevarious staged HEMTs as described herein can also enable more efficientpower delivery of an input voltage to a power transistor driving one ormore electrical components coupled thereto.

In one embodiment, an integrated circuit includes a driving circuit, acharge pump circuit, and a bootstrap circuit. The driving circuit has afirst stage and a second stage and is configured to provide an overdrivevoltage. The charge pump circuit is coupled between the first stage andthe second stage and is configured to generate a dynamic voltage greaterthan the overdrive voltage. The bootstrap circuit is coupled to thecharge pump circuit and configured to increase the overdrive voltage ofthe driving circuit.

In another embodiment, a method includes receiving, by a charge pumpcircuit of an integrated circuit, an input voltage. The charge pumpcircuit generates a dynamic charge pump voltage and is configured todrive a first voltage stage and a second voltage stage of the integratedcircuit. The charge pump circuit provides the dynamic charge pumpvoltage to a bootstrap circuit. The bootstrap circuit generates aboosted voltage based on the dynamic charge pump voltage to the firststage. The second voltage stage generates an overdrive voltage based onthe boosted voltage to drive a power transistor.

In yet another embodiment, a system includes a high-side driver, acharge pump circuit, and a power transistor. The high-side driver has aplurality of staged HEMTs configured to provide an overdrive voltage.The charge pump circuit is coupled between a first portion of theplurality of staged HEMTs and a second portion of the plurality ofstaged HEMTs. The charge pump circuit is configured to generate adynamic charge-pump voltage greater than the overdrive voltage. Thepower transistor is coupled to an output to the high-side driver and oneor more electrical components and configured to provide a voltage basedon the overdrive voltage to the one or more electronic components.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. An integrated circuit comprising: a drivingcircuit having a first stage and a second stage, the driving circuitconfigured to provide an overdrive voltage, wherein the first stagecomprises a depletion-mode high electron mobility transistor (D-HEMT)and the first stage and the second stage have a shared voltage input; acharge pump circuit coupled between the D-HEMT and the second stage,wherein the charge pump circuit is configured to generate a dynamicvoltage greater than the overdrive voltage; and a bootstrap circuitcoupled to the charge pump circuit, wherein the bootstrap circuit isconfigured to increase the overdrive voltage of the driving circuit. 2.The integrated circuit of claim 1, further comprising a power transistorcoupled to the driving circuit, wherein the overdrive voltage drives thepower transistor.
 3. The integrated circuit of claim 1, wherein thebootstrap circuit comprises: a bootstrap diode having a cathode terminalcoupled to the second stage; and a bootstrap capacitor coupled betweenthe cathode terminal and a output pin of the driving circuit.
 4. Theintegrated circuit of claim 1, wherein the first stage further comprisesa first enhanced-mode high electron mobility transistor (E-HEMT) and thesecond stage comprises a second and third enhanced-mode high electronmobility transistor (E-HEMT), wherein a gate terminal of the D-HEMT iscoupled to a source/drain terminal of the first E-HEMT and asource/drain terminal of the D-HEMT is coupled to the charge pumpcircuit.
 5. The integrated circuit of claim 4, wherein the first E-HEMTand the second E-HEMT are in an off-state at a zero gate-source voltageand wherein the D-HEMT is operational when a voltage of zero is appliedto a gate of the D-HEMT and non-operational when a negative voltage isapplied to the gate.
 6. The integrated circuit of claim 1, wherein thedriving circuit further comprises a third stage having a pair ofenhanced-mode high electron mobility transistors (E-HEMT).
 7. Theintegrated circuit of claim 3, wherein the driving circuit furthercomprises a fourth stage having a first enhanced-mode high electronmobility transistor (E-HEMT), a second E-HEMT, and a third E-HEMT, thefirst E-HEMT having a first source/drain terminal and a gate terminalcoupled to the cathode terminal of the bootstrap diode.
 8. Theintegrated circuit of claim 1, further comprising an internal bootstrapcircuit having a diode coupled between the charge pump circuit and thefirst stage and a capacitor coupled between the diode and a referencevoltage pin.
 9. The integrated circuit of claim 1, further comprising aboot-strapped inverting buffer circuit configured to reduce an inputload of the first stage.
 10. A method comprising: receiving, by a chargepump circuit of an integrated circuit, an input voltage; generating, bythe charge pump circuit, a dynamic charge pump voltage configured todrive a first voltage stage and a second voltage stage of the integratedcircuit, wherein the first voltage stage comprises a depletion-mode highelectron mobility transistor (D-HEMT), and the charge pump circuit iscoupled between the D-HEMT and the second voltage stage; providing, bycharge pump circuit, the dynamic charge pump voltage to a bootstrapcircuit, wherein the bootstrap circuit is coupled to the charge pumpcircuit; generating, by the bootstrap circuit, a boosted voltage basedon the dynamic charge pump voltage to the first stage; receiving, by thefirst voltage stage and the second voltage stage, a shared voltageinput; and generating, by the second voltage stage, an overdrive voltagebased on the boosted voltage to drive a power transistor.
 11. The methodof claim 10, wherein the overdrive voltage exceeds a minimum voltagethreshold of the power transistor.
 12. The method of claim 10, furthercomprising: minimizing a static current of the first stage and thesecond stage; and modifying, by the bootstrap circuit, an impedance ofthe first stage to minimize the static current.
 13. A system comprising:a high-side driver having a plurality of staged high electron mobilitytransistors (HEMTs), the high-side driver configured to provide anoverdrive voltage; a charge pump circuit coupled between a first portionof the plurality of staged HEMTs and a second portion of the pluralityof staged HEMTs, the first portion comprising a depletion-mode HEMT(D-HEMT), the charge pump is configured to generate a dynamiccharge-pump voltage greater than the overdrive voltage, wherein thefirst portion and the second portion have a shared voltage input; and apower transistor coupled between the high-side driver and one or moreelectrical components, wherein the power transistor is configured toprovide a voltage based on the overdrive voltage to the one or moreelectronic components.
 14. The system of claim 13, further comprising abootstrap circuit coupled between an output pin and the charge pumpcircuit configured to increase the overdrive voltage of the high-sidedriver.
 15. The system of claim 14, wherein the bootstrap circuitcomprises: a bootstrap diode having a cathode terminal coupled to one ofthe plurality of staged HEMTs; and a bootstrap capacitor coupled betweenthe cathode terminal and the output pin of the high-side driver.
 16. Thesystem of claim 13, wherein one of the plurality of staged HEMTscomprises a first enhanced-mode high electron mobility transistor(E-HEMT), and another of the plurality of the staged HEMTs comprises asecond and third enhanced-mode high electron mobility transistor(E-HEMT), wherein a gate terminal of the D-HEMT is coupled to asource/drain terminal of the first E-HEMT and a source/drain terminal ofthe D-HEMT is coupled to the charge pump circuit.
 17. The system ofclaim 16, wherein the first E-HEMT and the second E-HEMT are in anoff-state at a zero gate-source voltage and wherein the D-HEMT isoperational when a voltage of zero is applied to a gate of the D-HEMTand non-operational when a negative voltage is applied to the gate. 18.The integrated circuit of claim 13, wherein the plurality of stagedHEMTS includes a pair of enhanced-mode high electron mobilitytransistors (E-HEMT).
 19. The system of claim 16, wherein the pluralityof staged HEMTs further comprises a fourth stage having a firstenhanced-mode high electron mobility transistor (E-HEMT), a secondE-HEMT, and a third E-HEMT, the first E-HEMT having a first source/drainterminal and a gate terminal coupled to the cathode terminal of thebootstrap diode.
 20. The system of claim 13, further comprising aninternal bootstrap circuit having a diode coupled between the chargepump circuit and one of the plurality of HEMTs and a capacitor coupledbetween the diode and a reference voltage pin.